The prognosis in cancer of the breast is dependent on the likelihood of metastasis and ensuring recurrence of the disease. The mechanism of metastatic progression is probably not random colonization. There is a requirement for a significant capacity to construct the connective tissue and vascular framework which favors the survival and progression of the neoplastic growth. These are not likely to be random events, but should depend on specific, definable characteristics of the particular patient and tumor. With the support of this grant, we have secured the active collaboration of the clinical oncology community and, within the framework of our cancer center, have initiated a long range breast cancer prognostic study. This study seeks to define the specific, biological characteristics of large numbers of human, primary breast tumors and those host factors which are to be correlated with tumor development and metastasis. This includes immunological, virological, endocrinological, physiological and cell surface properties. The prognostic effectiveness of the host and tumor characteristics will be determined ultimately by the recurrence of tumors in this same patient population. Pathologic criteria can, with a varying degree of certainty, predict the aggressiveness of a tumor and thus aid in evaluation and monitoring of experimental protocols. Detailed characterization and long-term monitoring of the tumor cell and host variables in significant numbers of patients under coordinated clinical management can provide the information needed for advancing breast cancer control. This study also presents the opportunity to gain further insights into the basic mechanisms of metastatic progression.